This invention relates generally to x-ray imaging including computed tomography (CT), and more particularly the invention relates to correcting detected CT signals for scatter radiation.
Computer tomography is an established medical technique for visualizing internal organs with high resolution. Both fan beams and cone beams of x-rays are employed in CT
An x-ray system with a large area detector, such as is used for cone-beam CT (CBCT), typically has high scatter. Scatter causes severe distortions and contrast loss in the reconstructed images, and developing an effective scatter correction method is still a major challenge. Many methods have been proposed in the literature and provide significant improvement in image quality, although drawbacks still exist. One category of the scatter control techniques includes hardware-based methods, such as anti-scatter grid, air gap, scatter measurement using a beam stop array etc. These approaches suppress or correct for the presence of scatter by modifying the x-ray system. An alternative approach using software-based methods estimates and corrects for the scatter based on the system geometry and imaged object, and it has been shown for some applications that effective scatter control can be achieved. To combine the strengths of different types of correction methods, hybrid approaches are also often used which could provide well balanced tradeoffs among correction effectiveness, calculation time, exposure loss, dose increase, and the like.
The present invention is directed providing an improved method of x-ray scatter estimation in detected CT signals.